The long range objective of this research is to elucidate the pathophysiological mechanisms of pelvic pain in order to develop better strategies for alleviating pelvic pain syndromes in female and male patients. Chronic pelvic pain syndromes are a major challenge to the clinician, and treatment strategies, including medical and surgical approaches, are often unsuccessful. The neurophysiological mechanisms underlying pelvic pain are poorly understood. The use of animal models is a necessary step in understanding the underlying neurophysiological and neuropharmacological mechanisms of pelvic pain. The aim of the present studies is to develop an animal model of uterine pain using the rat, to obtain detailed information about the spinal pathways that process nociceptive afferent input from the uterus, and to assess the effects of peripheral opioid application on the neurophysiological processing of nociceptive input from the uterus. Specific Aim 1 examines the neurophysiological characteristics of dorsal horn neurons that respond to noxious uterine stimulation. The understanding of these characteristics will be the basis for future pharmacological interventions to alleviate pain from the uterus. Specific Aim 2 is targeted to answer the question: What are the peripheral effects of opioids on the spinal cord processing of nociceptive information from the uterus? Recently exogenous opioid agonists have been shown to have analgesic effects when administered in the vicinity of peripheral nerve terminals. This has been demonstrated in animal experiments as well as in patients with somatic pain, however no data are available regarding uterine pain. These studies should provide fundamental new information concerning the neurophysiological mechanisms of uterine pain. They are the first studies, which attempt to examine, whether peripherally applied modulate neurophysiological mechanisms of uterine pain. The results of these studies may rapidly contribute to the development of new pharmacological approaches to treat uterine pain syndromes.